Closure lid with a pressure-controlled or temperature-controlled directional control valve for an expansion tank and cooling system of an internal combustion engine

ABSTRACT

A closure lid for an expansion tank of a cooling system of an internal combustion engine has integrated therein a directional control valve that decouples the expansion tank from the cooling circuit by pressure control or temperature control and integrates the expansion tank again into the cooling circuit after the internal combustion engine has reached its operating temperature.

For cooling the waste heat produced in operation of internal combustionengines, water cooling is accepted practice in automobiles as well as incommercial vehicles.

The most important components of such water cooling are the water jacketof the internal combustion engine itself, a circulation pump, referredto also as water pump, an air-cooling agent cooler, a cooling agentexpansion tank, and a thermostat.

In FIG. 7, such a cooling system is illustrated in a greatly simplifiedand schematic way.

The cooling agent expansion tank, in the following also referred to asexpansion tank, has several functions. On the one hand, it serves toreliably separate gas bubbles generated during cavitation primarily atthe suction side of the pump.

Also, the air volume in the expansion tank serves to enable fastpressure build-up upon heating and expansion of the cooling agent and toprevent escape of cooling agent when shutting down.

Because today's cooling systems are operated with overpressure, theexpansion tank is closed off by a closure cap or a lid that, uponsurpassing the permissible maximum pressure, enables blow-off into theenvironment. A further function of this closure lid resides in thatopening of the expansion tank is to be prevented as long as thetemperature of the cooling agent is elevated and, as a result of this,also the pressure of the cooling agent is significantly higher than theambient pressure.

For environmental protection reasons and reasons of convenience, thereis the desire to provide a cooling system that upon cold start of theinternal combustion engine enables heating of the internal combustionengine as quickly as possible. This reduces fuel consumption in the coldstart phase, and emissions in the cold start phase are alsosignificantly reduced. A further goal is to be able to heat as quicklyas possible the interior of the vehicle.

The invention has the object to provide a closure lid and a coolingsystem of an internal combustion engine which support these goals.

This object is solved according to the invention by a closure lidaccording to claim 1.

Advantageous configurations of the directional control valve accordingto the invention and its integration into the closure lid are claimed inthe dependent claims and will be explained in detail in the following inthe drawings and their description.

Because the directional control valve according to the invention openswith its outlet into the expansion tank, the expansion tank is separatedhydraulically from the rest of the cooling system until the coolingwater circulating in the rest of the cooling system has reached acertain minimum temperature and, as a result thereof, a predeterminedoverpressure is established in the cooling system.

As long as the minimum temperature or the overpressure has not yet beenreached, the directional control valve is closed and the volume of thecooling agent circuit is reduced in the cold start phase by the contentsof the expansion tank so that the “active” part of the cooling systemand the internal combustion engine will heat up faster.

The advantage of a pressure-controlled directional control valve is tobe viewed in that, independent of the positioning of the expansion tank,the pressure at the inlet side of the directional control valvecorresponds to the pressure which is present in the cooling system.Accordingly, the pressure is a very direct and reliable criterion foropening the directional control valve after reaching operatingtemperature. Of course, it is also possible to use atemperature-controlled directional control valve in the closure lidinstead of a pressure-controlled directional control valve.

In the embodiment illustrated in the Figures, it is advantageous whenthe pressure spring is supported with one end at a spring plate fixedlysecured within the housing and the pressure spring is supported with theother end at the valve member.

In a service position of the lid, the entire directional control valveis moved out from a seal-tight contact with a housing so that thecooling water can bypass the directional control valve. By integrationof the directional control valve in the closure lid, this functionalityis realized without any additional costs.

In other words, when the cover is tightly screwed on and a pressurebuild-up in the cooling system is thus possible, the directional controlvalve according to the invention opens only at the time when aconstructively predetermined overpressure in the system exists.

It has been found in many situations to be advantageous when the sealingseat is designed as a plate seat. In this way, the manufacture issimplified, a satisfactory seal-tightness is also achieved, and thedirectional control valve according to the invention is robust withregard to smaller contaminations or deposits.

Further advantages and advantageous embodiments can be taken from thefollowing drawings, their description, and the claims.

Drawings

It is shown in:

FIG. 1 a longitudinal section of a first embodiment of apressure-controlled directional control valve according to the inventionin the closed state;

FIG. 2 the pressure-controlled directional control valve in the openstate;

FIG. 3 the closure lid in the service position; and

FIG. 4 a schematic illustration of a cooling system of an internalcombustion engine.

DESCRIPTION OF THE EMBODIMENTS

In FIG. 1, a part of an expansion tank 1 with screwed-on safety closurelid 2 is illustrated in section. The safety closure lid 2 comprises inthe upper part an overpressure valve, an underpressure valve, and anunscrewing safety (no reference character) that will not be explained inmore detail.

In connection with the invention, it is however important that the lid 2is screwed into a socket 1 a of an expansion tank 1. In FIG. 1, theso-called closed position is reached. This means that the lid 2 can nolonger be screwed any deeper into the socket (without referencecharacter) of the expansion tank 1.

In the closed position, the lid 2 seals the expansion tank 1 relative tothe environment. The safety valve (no reference character) integratedinto the lid 2 opens only when a pre-adjusted overpressure is reached inorder to avoid impermissibly high pressure loads of the cooling system.Alternatively, the directional control valve can also opentemperature-dependent.

In the lower section of the lid 2 in FIG. 1, a pressure-controlleddirectional control valve 8 according to the invention is integrated.

The directional control valve 8 is integrated into a housing 4 which ispart of the lid 2. The housing 4 delimits together with the socket 1 aof the expansion tank 1 an annular space 5. A bypass line 6 that is partof the cooling circuit of the internal combustion engine (see FIG. 4)opens into the annular space 5. The annular space 5 is delimited by twoO-ring seals 10 and 12. The section of the housing 4 between the O-rings10 and 12 is identified by reference character 13.

The directional control valve 8 is arranged in a recess 14 in theinterior of the housing 4.

At a step (no reference character) of the recess 14 there is an annularvalve seat 16. The valve seat 16 interacts with a cup-shaped valvemember 18. At a collar or web 20 of the valve member 18, a sealing edge22 is formed which interacts with the valve seat 16.

In the cup of the valve member 18, a pressure spring 24 is inserted thatis supported on a spring plate 26. The spring plate 26 is connectedfixedly with the housing 4.

The closed position illustrated in FIG. 1, the pressure spring 24 forcesthe valve member 18 with its sealing edge 22 against the valve seat 16and interrupts the hydraulic connection between the bypass line 6 andthe expansion tank 1. The bypass line 6 is connected hydraulically withthe inlet of the directional control valve 8 while the outlet of thedirectional valve 8 is connected with the expansion tank 1.

Reference character 28 identifies a hydraulic connection between theannular space 5 and the part of the recess which is arranged in FIG. 1above the valve member 18.

Because of the hydraulic connection 28, the same pressure is acting onthe valve member 18 as in the annular space 5 and in the bypass line 6.The thus resulting hydraulic force counteracts the force which isexerted by the pressure spring 24. When the hydraulic force that isacting on the valve member 18 is greater than the force of the pressurespring 24, the valve member 18 is lifted off the valve seat 16 andestablishes a hydraulic connection between the bypass line 6 and theexpansion tank 1.

It is assumed in this context that the pressure in the expansion tank 1corresponds approximately to the ambient pressure, in any case howeveris lower than in the annular space 5 as long as the directional controlvalve 8 is closed.

The opening pressure of the directional control valve 8 is determined bythe pretension of the pressure spring 24 and the surface which isenclosed by the sealing edge 22.

In FIG. 2, the open directional control valve 8 is illustrated. As soonas the directional control valve 8 is opened, cooling liquid can flowfrom the bypass line 6 into the expansion tank 1 so that the expansiontank 1 becomes part of the cooling circuit.

In FIG. 3, the lid 2 is illustrated in the so-called service position.In the service position, the lid 2 is rotated relative to the closedposition illustrated in FIG. 1 by approximately one turn, correspondingto 360 degrees or approximately 3 millimeter, out of the socket of theexpansion tank 1. The service position is important when thepressure-controlled directional control valve 8 according to theinvention is to be deactivated by a car mechanic in the shop in order tobe able to check the function of the cooling system without having tobring the cooling system or the internal combustion engine up tooperating temperature beforehand.

When the lid 2 has been brought into the service position illustrated inFIG. 3, the lower O-ring 12 in FIG. 3 lifts off the truncatedcone-shaped diameter constriction 30 of the socket 1 a so that ahydraulic “short-circuiting” between the bypass line 6 and the expansiontank 1 is generated. Now the expansion tank 1 is integrated into thecooling water circuit, independent of the pressure or temperature levelof the cooling water.

In FIG. 4, a cooling system with an expansion tank 1 is nowschematically illustrated wherein the expansion tank 1 is provided with,or is closed off by, a lid 2 according to the invention.

An internal combustion engine carries the reference character 61. Anair-water cooler carries the reference character 63. A cooling agentpump 65 circulates the water through lines (without referencecharacters) in the cooling circuit. A thermostat valve is provided withreference character 67. The expansion tank 1 and the corresponding lid 2are only schematically indicated.

The bypass line 6, which connects the expansion tank 1 with the coolingwater circuit when the directional control valve in the closure lid 2 isopen, also has reference character 6 in FIG. 4.

What is claimed is: 1.-9. (canceled)
 10. A closure lid for an expansion tank of a cooling system of an internal combustion engine, the closure lid comprising: a housing; a directional control valve integrated in the housing; the directional control valve having an outlet connected to the expansion tank; the directional control valve having an inlet connected to a bypass line; the directional control valve adapted to open and close by pressure control or temperature control.
 11. The closure lid according to claim 10, wherein the housing has a section delimiting in annular space, wherein the housing has a recess in which the directional control valve is disposed, and wherein a hydraulic connection exists between the recess and the section of the housing delimiting the annular space.
 12. The closure lid according to claim 11, wherein a valve seat of the directional control valve is formed or arranged in the recess.
 13. The closure lid according to claim 12, wherein the directional control valve comprises a valve member and the valve member interacts with the valve seat.
 14. The closure lid according to claim 13, wherein the valve member is spring-loaded or is actuated by a bimetal.
 15. The closure lid according to claim 14, further comprising a pressure spring that spring-loads the valve member, wherein the pressure spring is arranged between the valve member and a spring plate that is attached at least indirectly to the housing.
 16. The closure lid according to claim 13, wherein the valve seat is a plate seat.
 17. The closure lid according to claim 10, wherein a blocking function of the directional control valve depends on a screw-in depth of the closure lid in a socket of the expansion tank.
 18. A cooling circuit for an internal combustion engine comprising an external cooling agent circuit and an expansion tank, wherein the external cooling agent circuit has an inlet and a return line and supplies waste heat of the internal combustion engine to a cooler of the cooling agent circuit, wherein the expansion tank is connected by a bypass line and by an outlet hydraulically to the cooling agent circuit, wherein the expansion tank has a socket and a closure lid embodied according to claim 10 and adapted to close off the socket. 